Smiling at pictures of me smiling

Whenever I look at a picture of myself smiling (a rare occasion, mind you), I always smile back. Not only that, I smile the exact same smile I smiled in the picture. I think I've done this all my life, and to be honest I have no idea why I noticed I do it at all, because it is a completely subconscious response. I don't even know how my brain rationalizes it. Am I critiquing myself? Does it genuinely make me happy? I'm really drawing a blank here. I wonder if other people do this too.